Background images are defined on the Report Properties session under the tab:

To enable background images, the Enable Background Image box must be checked.
There are two types of background image: static and dynamic. Our example depicts a static background image: one where the image shown never changes.
A dynamic background image can be displayed from the xTuple images table based on the results of a the SQL in a query source. The column field would then reference the image_data column which contains the image data. Company logos, product images, and employee photos, just to name a few, can be stored in the images table and pulled dynamically into a report through the SQL in a query source.
Within the tab there are three sub-tabs: , , and .